The present invention relates to a cleaning device carried on, for example, an image forming apparatus of an electrophotographic system and to an image forming apparatus.
Presently, in an image forming apparatus of an electrophotographic system, for example, there is commonly used an image forming apparatus equipped with a latent image carrier composed of an organic photoreceptor containing organic photoconductive substances. The reason for this is as follows; that is, an organic photoreceptor has many advantageous points compared with other image carriers, including that materials coping with various exposure light sources covering a visible light through infrared radiation are easily developed, materials which cause no environmental pollution can be selected, and manufacturing cost is low.
In the image forming apparatus of this kind, there is known an image forming apparatus that is equipped, as a means to eliminate residual toner such as not-transferred toner or after-transfer-residual toner on an organic photoreceptor, with a cleaning device which is of a blade cleaning system to bring a flat cleaning blade made of an elastic object to be in contact with a surface of the organic photoreceptor and thereby to eliminate residual toner on the organic photoreceptor.
However, with regard to the organic photoreceptor, its mechanical strength is small, and thereby, deterioration or cracks on its surface are easily caused when making many prints, while, energy of contact with toner for visualizing an electrostatic latent image formed on the surface of the organic photoreceptor is great, and thereby, various problems described below are easily caused in the cleaning step to eliminate residual toner which has passed through a transfer area.
For example, because of the contact energy which is great, there are easily caused phenomena such as xe2x80x9cblade eversionxe2x80x9d which means that a tip edge of the cleaning blade that is in contact with a surface of the organic photoreceptor follows to move in the moving direction of the organic photoreceptor to be reversed, xe2x80x9cblade boundxe2x80x9d which means that the cleaning blade bounds on the surface of the organic photoreceptor, while being affected by the force acting in the direction to compress and deform the cleaning blade that is caused by movement of the organic photoreceptor, or xe2x80x9cblade squeakingxe2x80x9d which means that a minute vibration caused at a portion where the cleaning blade is in contact with the surface of the organic photoreceptor is resonant with the organic photoreceptor to produce high metallic sound.
On the other hand, in the image forming apparatus of an electrophotographic system, toner particles are now required to be small in size from the viewpoint of high image quality of an image, and a polymerization method such as, for example, an emulsion polymerization method or a suspension polymerization method is favorably used as a method to obtain the aforementioned toner particle.
However, adhesive power between toner particles and an organic photoreceptor becomes greater as toner particles are made to smaller, and thereby, removing of residual toner on the organic photoreceptor becomes more difficult, and when the so-called polymerization toner produced by the polymerization method is used, in particular, a form of a toner particle becomes to be closer to a spherical shape. Therefore, a toner particle rolls on the organic photoreceptor to cause easily a cleaning failure which means that the toner particle slips through the cleaning blade and is called the so-called xe2x80x9cslipping-throughxe2x80x9d, which causes a problem that it is more difficult to remove residual toner on the organic photoreceptor. In particular, the surface of the organic photoreceptor tends to be worn out, and when toner sticks to the unevenness on the surface generated by wear, slipping-through of a few toner is generated for a long time, and these toner particles which have slipped through contaminate charging members (charging wires and charging rollers), resulting in a problem that forming of images having high image quality is difficult.
For preventing occurrence of such cleaning failure, TOKKAIHEI No. 3-189675, for example, discloses a cleaning system wherein mechanical cleaning by a cleaning blade and electrostatic cleaning are used together.
To be concrete, in the structure of the cleaning system, a brush roller made of conductive material is installed at the position which is upstream side of the cleaning blade in the direction of movement of a latent image carrier, and on this brush roller, there is impressed appropriate-sized bias voltage whose polarity is opposite to that of residual toner on the latent image carrier, for example, and thereby, the cleaning efficiency has been improved by both a mechanical cleaning effect by means of a cleaning blade and an electrostatic cleaning effect by means of the brush roller.
However, in the image forming apparatus of the aforementioned structure, the greater part of residual toner on the latent image carrier are removed by the brush roller located at the upstream side in the direction of movement of the latent image carrier, and thereby, an amount of residual toner arriving at the cleaning blade is extremely small in many cases, thus, aforementioned blade eversion and blade squeaking tend to be caused, resulting in a problem that stable forming of images having high image quality for a long time is difficult.
Further, to prevent occurrence of cleaning failure like that stated above, it has been suggested to make the particle shape of toner to be used to be amorphous, for example, to make a form of a particle of toner to be a shape of an ellipse, or to make a surface shape of a particle of toner to be of an unevenness shape, but none of them has been a solution in the actual conditions.
The invention has been achieved based on the aforementioned circumstances, and its object is to provide a cleaning device which is provided with a cleaning blade and is capable of exhibiting high cleaning power stably for a long time.
Another object of the invention is to provide an image forming apparatus which is capable of removing surely residual toner on a latent image carrier and thereby is capable of forming stably images having high image quality for a long time.
The cleaning device of the invention is provided with a cleaning blade mechanism that comprises a cleaning blade arranged so that its tip edge may touch the surface of a cylindrical latent image carrier that is driven to rotate and a supporting member that is positioned on the outer surface of a base end portion of the cleaning blade to urge the cleaning blade to be in contact with the surface of the latent image carrier, and in the cleaning blade mechanism, there is provided a flexible and laminar vibration-damping member which is held at its base end portion by the supporting member to extend in the same direction as that of the cleaning blade, and on the tip end portion of the vibration-damping member, there are formed slit-shaped slits so that a plurality of tab portions may be formed in the axial direction of the latent image carrier, and a tip edge of the tab portion is positioned at the outer surface of the cleaning blade.
On the cleaning device of the invention, it is preferable that a ratio of the protruded length of the vibration-damping member extending beyond the tip edge of the supporting member to that of the cleaning blade extending beyond the tip edge of the supporting member is greater than 0.1 and is not more than 0.9.
On the cleaning device of the invention, it is preferable that a length of the tab portion of the vibration-damping member in the direction of the axis of the latent image carrier is within a range of 1/100-1/10 of the length of the cleaning blade in the axial direction, and it is further preferable that a depth of a slit formed on the tip end portion is in the size ranging from 1/10 to 1/1 of the protruded length of the vibration-damping member.
The image forming apparatus of the invention is characterized in that residual toner on the latent image carrier is removed by the aforementioned cleaning device at the position for a toner image formed by a toner image forming mechanism where the toner image has passed a transfer area where the toner image is transferred onto a recording material.
Further, on the image forming apparatus of the invention, it is preferable that toner used in the toner image forming mechanism satisfies one or two, or all of the following conditions (1)-(3).
(1) Toner composed of toner particles wherein a percentage of toner particles whose shape factor is within a range of 1.2-1.6 is 65 number % or more, and a variation coefficient of the shape factor is 16% or less.
(2) Toner composed of toner particles wherein a variation coefficient of the shape factor is 16% or less, and the number variation coefficient in number particle size distribution is 27% or less.
(3) Toner composed of toner particles wherein a percentage of toner particles having no corners is 50 number % or more.
Effect
In the cleaning device of the invention, a vibration of the cleaning blade is damped by and absorbed into a vibration-damping member, because the vibration-damping member having flexibility is in contact with the cleaning blade for the whole area of the latent image carrier in its axial direction, thus, it is possible to control the vibration of the cleaning blade to be small, without impeding original effect and function of the cleaning blade, and further it is possible to surely prevent occurrence of blade bound, blade eversion, blade squeaking or slipping-through of toner, because each tab portion can exhibit vibration-damping functions independently each other, which makes it possible to exhibit high cleaning effect for certain.
Even in the case of variation of pressing force of the cleaning blade against a photoreceptor caused by deformation of the cleaning blade that results from environmental fluctuations, the vibration-damping member follows the cleaning blade, and thereby, occurrence of great variation of contact load of the cleaning blade against the latent image carrier is repressed, thus, occurrence of blade bound, blade eversion, blade squeaking or slipping-through of toner can be prevented surely, and expected cleaning effect can be exhibited stably despite the environmental fluctuations.
In the image forming apparatus of the invention wherein the aforementioned cleaning device is provided, it is possible to prevent surely occurrence of blade squeaking, blade bound or blade eversion, and to exhibit stable cleaning effect for environmental fluctuations, and therefore, it is possible to remove residual toner on the latent image carrier for certain, and to form stably images having high image quality for a long time.
In the second structure of the cleaning device of the invention, there are provided a cleaning blade mechanism having a cleaning blade arranged so that its tip edge may touch the surface of a cylindrical latent image carrier that is driven to rotate, a cleaning roller mechanism having a cleaning roller that is arranged so that it may touch the surface of the latent image carrier at the position which is upstream side of the cleaning blade in the direction of movement of the latent image carrier and may rotate around the rotary shaft extending in the axial direction of the latent image carrier, and a bias voltage impressing means that impresses bias voltage on the cleaning roller, and in the cleaning blade mechanism, a supporting member that is positioned on the outer surface of a supporting member that is positioned on the outer surface of a base end portion of the cleaning blade to urge the cleaning blade to be in contact with the surface of the latent image carrier, and there is provided a flexible and laminar vibration-damping member which is held at its base end portion by the supporting member to extend in the same direction as that of the cleaning blade, while on the tip end portion of the vibration-damping member, there are formed slit-shaped slits so that a plurality of tab portions may be formed in the axial direction of the latent image carrier, and a tip edge of the tab portion is positioned at the outer surface of the cleaning blade.
On the second structure of the cleaning device of the invention, it is preferable that a ratio of the protruded length of the vibration-damping member extending beyond the tip edge of the supporting member to that of the cleaning blade extending beyond the tip edge of the supporting member is greater than 0.1 and is not more than 0.9.
On the second structure of the cleaning device of the invention, it is preferable that a length of the tab portion of the vibration-damping member in the direction of the axis of the latent image carrier is within a range of 1/100-1/10 of the length of the cleaning blade in the axial direction, and it is further preferable that a depth of a slit formed on the tip end portion is in the size ranging from 1/10 to 1/1 of the protruded length of the vibration-damping member.
Further, it is preferable that a bias voltage impressing means is a constant-current power supply.
In the second structure of the image forming apparatus of the invention, there are provided a cylindrical latent image carrier that is driven to rotate, a toner image forming mechanism that forms a toner image on the latent image carrier with toner, and a cleaning device that removes residual toner on the latent image carrier at the position for the toner image on the latent image carrier to be transferred onto a recording material, and the cleaning device is provided with a cleaning blade mechanism having a cleaning blade arranged so that its tip edge may touch the surface of a latent image carrier, a cleaning roller mechanism having a cleaning roller that is arranged so that it may touch the surface of the latent image carrier at the position which is upstream side of the cleaning blade in the direction of movement of the latent image carrier and may rotate around the rotary shaft extending in the axial direction of the latent image carrier, and with a bias voltage impressing means that impresses bias voltage on the cleaning roller, while, in the cleaning blade mechanism, a supporting member that is positioned on the outer surface of a supporting member that is positioned on the outer surface of a base end portion of the cleaning blade to urge the cleaning blade to be in contact with the surface of the latent image carrier, and there is provided a flexible and laminar vibration-damping member which is held at its base end portion by the supporting member to extend in the same direction as that of the cleaning blade, and on the tip end portion of the vibration-damping member, there are formed slit-shaped slits so that a plurality of tab portions may be formed in the axial direction of the latent image carrier, and a tip edge of the tab portion is positioned at the outer surface of the cleaning blade.
On the second structure of the image forming apparatus of the invention, it is preferable that a ratio of the protruded length of the vibration-damping member extending beyond the tip edge of the supporting member to that of the cleaning blade extending beyond the tip edge of the supporting member is greater than 0.1 and is not more than 0.9.
On the second structure of the image forming apparatus of the invention, it is preferable that a length of the tab portion of the vibration-damping member in the direction of the axis of the latent image carrier is within a range of 1/100-1/10 of the length of the cleaning blade in the axial direction, and it is further preferable that a depth of a slit formed on the tip end portion is in the size ranging from 1/10 to 1/1 of the protruded length of the vibration-damping member.
It is further preferable that a bias voltage impressing means is a constant-current power supply.
Further, on the second structure of the image forming apparatus of the invention, it is preferable that toner used in the toner image forming mechanism satisfies one or two, or all of the following conditions (1)-(3).
(1) Toner composed of toner particles wherein a percentage of toner particles whose shape factor is within a range of 1.2-1.6 is 65 number % or more, and a variation coefficient of the shape factor is 16% or less.
(2) Toner composed of toner particles wherein a variation coefficient of the shape factor is 16% or less, and the number variation coefficient in number particle size distribution is 27% or less.
(3) Toner composed of toner particles wherein a percentage of toner particles having no corners is 50 number % or more.
In the second structure of the cleaning device of the invention, mechanical cleaning by a cleaning blade is carried out in addition to electrostatic cleaning by the cleaning roller mechanism, and basically high cleaning effect is exhibited, and residual toner on the latent image carrier can surely be removed accordingly.
Further, in the cleaning blade mechanism, a vibration-damping member having flexibility is in contact with a cleaning blade for the whole area of the cleaning blade in its lateral direction, and therefore, a vibration of the cleaning blade is damped by and absorbed into a vibration-damping member, and it is possible to control the vibration of the cleaning blade to be small, and to surely prevent occurrence of blade bound, blade eversion, blade squeaking or slipping-through of toner, without impeding original effect and function of the cleaning blade, because each tab portion can exhibit vibration-damping functions independently each other, which makes it possible to exhibit high cleaning effect for certain.